1. Field of the Invention
The invention relates to manipulation methods of multiple spanning tree (MST) protocols, and in particular to compatible methods and systems for multiple spanning tree (MST) protocols.
2. Description of the Related Art
Generally, spanning tree protocol (STP) is a communication and management method and mechanism based on the IEEE 802.1d Standard. STP is supported in bridge devices of a network and used to reduce path repeats and redundancy thereof. STP also avoids loops in a network topology. Within a network, data is transmitted in packets. A switch is a device to filter or forward data packets among different local area networks (LANs).
With technical progress of networks, a physical LAN is usually divided into various virtual LANs (VLANs). Thus, one single STP cannot suitably fit requirements for the divided VLAN topology and therefore multiple spanning tree protocol (MSTP) is produced. MSTP can properly calculate multiple topologies for a network. A region is a manipulation unit for MSTP and switches located in the same region have the same MST parameters. Once a region is formed, all switches in the formed region are regarded as a large integrated switch.
MSTP can be established according to different standards, for example, IEEE 802.1s/802.1q Standard and Cisco Standard. Thus, a switch conforms to IEEE Standard is incompatible with Cisco Standard. Referring to FIGS. 1a-1c, a network environment includes switches 100, 102, and 104. The switch 102 is a Cisco switch (conforming to Cisco Standard) and the switch 104 is a standard switch (conforming to IEEE 802.1 Standard). If the switch 102 and 104 are set to form one region, the ideal region is 108 as shown in FIG. 1b. Because the Cisco switch is not compatible to the standard switch, the actual formed regions are 110 and 112 as shown in FIG. 1c. The Cisco switch forms a region 110 and the standard switch forms another region 112. The regions 110 and 112 cannot be integrated to one region.
Thus, compatible methods and systems for MSTPs are desirable.